So, I’ve mentioned before that Fluttershy is the best portrayal I’ve ever seen of someone suffering from avoidant personality disorder, and Twilight Sparkle is, according to Spoilers Below’s comment on my “Lesson Zero” post, a pretty good depiction of an OCD sufferer, at least in that episode.
But this leads naturally to the question of the other ponies. Do any of them suffer from any recognizable mental disorders? And the answer is, well, no. Not really.
Pinkie Pie is the obvious choice, because (as I discussed at length in my “Party of One” post) she clearly has some serious issues. But as near as I can tell (not being a professional therapist by any means, not that any doctor worth their degree would be willing to diagnose a patient based on a single 20-minute recording) Pinkie’s issues don’t actually map onto any one known disorder. Either she’s got something new, she’s suffering from a complex combination of multiple disorders, or (most likely) the creators were just messing around and made her generically “crazy.”
The other ponies don’t seem to have any recognizable disorders either, at least nothing that approaches the “danger to self or others” criterion. So no, Twilight, you’re wrong: Everypony in this town is not crazy.